Abstract Atmospheric CO2 increased in the 20th century and is expected to continue to do so in the 21st century, with resultant warming. Even so, the effects of these changes on the ecological systems, such as carbon sequestration in grassland ecosystems, are still poorly understood. To improve our understanding of the carbon balance, we developed a two-layer soil hydrology model for Terrestrial Ecosystem Model-Hydro Daily to simulate the carbon fluxes of moist grasslands more accurately. Using the outputs of two Representative Concentration Projection scenarios (RCP4.5 and 8.5) from five Coupled Model Inter-comparison Project Phase 5 climate models, we investigated if projected warming and rising atmospheric CO2 could stimulate net primary production (NPP), net ecosystem productivity (NEP), and ecosystem respiration of two highly productive grassland sites in the central Great Plains (USA) in the 21st century. Our study shows that elevated atmospheric CO2 has a fertilization effect in boosting NPP in grassland ecosystems, with a sensitivity of 0.53 gC m−2 yr−1 and 1.06 gC m−2 yr−1 under the RCP4.5 and RCP8.5 climate scenarios, respectively. Warming is more harmful to NPP in the grassland adapted to a warmer climate. Under the RCP4.5 scenario, both grassland sites likely experience a variable net ecosystem carbon exchange. However, the RCP8.5 scenario and accompanying severe warming would turn both grassland sites to net carbon sources by the end of the century, decreasing NEP by 0.97 gC m−2 yr−1 at the warmer site and by 0.96 gC m−2 yr−1 at the cooler site, driven by increased respiration and limited plant growth.

中文翻译：

---

使用 CMIP5 GCM 结果在美国中部大平原预测中草原生态系统的碳平衡变化以响应变暖和 CO2 升高

摘要 大气 CO2 在 20 世纪增加，预计在 21 世纪将继续增加，从而导致变暖。即便如此，这些变化对生态系统的影响，如草原生态系统的碳固存，仍然知之甚少。为了加深我们对碳平衡的理解，我们为陆地生态系统模型-Hydro Daily 开发了一个两层土壤水文模型，以更准确地模拟潮湿草原的碳通量。使用来自五个耦合模型比对项目第 5 阶段气候模型的两个代表性浓度预测情景（RCP4.5 和 8.5）的输出，我们调查了预测的变暖和大气 CO2 上升是否可以刺激净初级生产 (NPP)、净生态系统生产力(新经济政策), 21 世纪美国大平原中部两个高产草地的生态系统呼吸和呼吸。我们的研究表明，大气 CO2 升高对提高草地生态系统的 NPP 具有施肥效应，在 RCP4.5 和 RCP8.5 气候情景下，敏感性分别为 0.53 gC m-2 yr-1 和 1.06 gC m-2 yr-1 ， 分别。气候变暖对适应温暖气候的草地的NPP危害更大。在 RCP4.5 情景下，两个草地站点都可能经历可变的净生态系统碳交换。然而，到本世纪末，RCP8.5 情景和伴随的严重变暖将使两个草原站点都变成净碳源，使温暖站点的 NEP 降低 0.97 gC m-2 yr-1，并降低 0.96 gC m-2 yr -1 在较冷的地点，受呼吸增加和植物生长受限的驱动。